The primary goal for Steam Deck optimization is Memory Locking. When you increase the UMA Frame Buffer to 4GB, you are essentially telling the system to reserve a larger minimum slice of the 16GB total RAM specifically for the GPU. Using global launch options (via the Steam properties or Decky Loader) allows you to further optimize the Vulkan Shader Pipeline and DXVK (DirectX to Vulkan) translation, ensuring that the 4GB buffer is utilized with maximum efficiency.
Hardware Compatibility & Expectations
- BIOS Tweak Required: This guide assumes you have already entered the BIOS (Hold Volume+ and Power) and set UMA Frame Buffer Size to 4G.
- Storage Speed: High-end textures stored on a slow MicroSD card can still cause stutters regardless of VRAM. An NVMe SSD is recommended for this setup.
- Proton GE: These launch options work best when paired with Proton GE (GloriousEggroll), which includes latest patches for memory management.
Preparation: The BIOS Step
Before applying launch options, you must lock the hardware allocation:
- Shut down your Steam Deck.
- Hold Volume Up (+) and press the Power Button.
- Select Setup Utility > Advanced.
- Change UMA Frame Buffer Size from 1G to 4G.
- Save and Exit.
Recommended Global Launch Options
In the Steam Library, right-click any demanding game (e.g., Cyberpunk 2077, Elden Ring) and paste the following into the Launch Options box:
RADV_PERFTEST=sam,nggc %command%For DirectX 11/12 Games (Most AAA Titles):
DXVK_ASYNC=1 RADV_PERFTEST=sam %command%Pro Tip: Using
RADV_PERFTEST=samenables Smart Access Memory (Resizable BAR) logic for the integrated AMD GPU. This allows the CPU to access the entire 4GB VRAM buffer simultaneously, significantly reducing “1% Low” frame drops during asset-heavy scenes.
Key Parameters Explained
| Parameter | Recommended Value | Impact |
| RADV_PERFTEST=sam | Enabled | Enables Resizable BAR-like behavior; improves CPU-GPU data transfer speed. |
| DXVK_ASYNC=1 | Enabled | (Proton GE only) Compiles shaders in the background to prevent “shader-compilation stutter.” |
| mesa_glthread=true | Enabled | For OpenGL games (like Minecraft); offloads draw calls to a separate CPU thread. |
| RADV_PERFTEST=nggc | Enabled | Enables Next-Generation Geometry Culling, reducing GPU load in dense scenes. |
System-Level Optimization (CryoUtilities)
To truly benefit from the 4GB VRAM lock, it is highly recommended to use the CryoUtilities script. This tool modifies the Linux kernel’s “Swap” behavior to match the 4GB buffer:
- Swap File Size: Set to 16GB. This provides a massive safety net for the system RAM.
- Swappiness: Set to 1. This tells the Steam Deck to only use the SSD swap when absolutely necessary, keeping the 12GB of available system RAM as “clean” as possible.
- Huge Pages: Set to Enabled. This improves the efficiency of memory addressing for the CPU.
Troubleshooting & Common Fixes
- Game Crashes on Launch: Some older titles or indie games (like Hollow Knight) might dislike the 4GB lock and crash. If this happens, revert the BIOS to 1G for that specific game.
- Red Dead Redemption 2 Issues: RDR2 has a unique memory leak on Steam Deck. If it stutters, ensure you are using the
RADV_PERFTEST=samargument to help the engine manage the buffer. - Settings Resetting: SteamOS updates occasionally reset the UMA buffer to 1G. Always check the BIOS after a major “Stable” channel update.
Frequently Asked Questions (FAQ)
Does 4GB VRAM reduce my system RAM?
Yes. Since the Steam Deck has 16GB total, locking 4GB for the GPU leaves 12GB for the system/CPU. For most games, this is the “Golden Ratio.” Only a few titles (like The Last of Us Part I) might prefer more system RAM (1G VRAM setting).
Why use DXVK_ASYNC?
Without it, the game pauses for a millisecond every time a new shader (like an explosion or new area) is loaded. ASYNC allows the game to keep running while the shader is prepared, though it may cause temporary “ghosting” for a split second.
Is this safe for the OLED and LCD models?
Absolutely. This is a standard feature of the AMD APU. It does not “overclock” the hardware or void your warranty; it simply reallocates existing resources.
Conclusion and Expected Results
By locking the UMA buffer to 4GB and utilizing the sam and nggc launch flags, you are optimizing the Steam Deck for modern high-fidelity gaming. You can expect fewer sudden FPS dips, elimination of many “Memory Exhausted” error crashes, and a more consistent 30 or 40 FPS experience in open-world titles.